Some time ago I bought a book called The Transhumanist Reader, a collection of essays published last year by thinkers associated with the transhumanist movement. Transhumanists are a diverse bunch, but what they have in common is the desire to use technology to overcome what they see as the limitations of the human condition. Their goal, if you like, is to become post-human. 

"Post-human beings would no longer suffer from disease, aging and inevitable death," writes Max More in the book's introductory essay. "They would have vastly greater physical capability... much greater cognitive capabilities, and more refined emotions (more joy, less anger, or whatever changes each individual prefers).”

It's a vision of the human future that's as vivid as it is extraordinary, and it speaks to one of our species' deepest wishes: the longing for eternal life. "Consume my heart away;" Yeats wrote, "sick with desire and fastened to a dying animal. Gather me / Into the artifice of eternity." Alchemical texts, Egyptian funerary rites, Roman graffiti, and the poetry of Shakespeare – "So long lives this, and this gives life to thee" – all bear witness to the obstinacy of the human wish to live forever.